Zeolite 촉매를 이용한 Methyl - tert - Butyl Ether 의 합성

김건중,조병린,안화승,권이묵 한국화학공학회 1988 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.26 No.5

HZSM-5, HZSM-11, H-Mordenite및 HY型 zeolite를 觸媒로 사용하여 氣相 MTBE 合成實驗을 수행하였으며, zeolite 觸媒의 종류 및 반응조건에 따른 MTBE 生成관계를 硏究하였다. 각 觸媒들은 pyridine을 吸着시켜 TPD및 IR法으로 酸點의 세기와 종류를 측정하였으며, 觸媒의 酸性度 및 細孔構造的 特性에 연관지어 MTBE에 대한 선택성을 검토하였다. HZSM-5上에서는 methanol의 脫水에 따른 DME의 生成이 관찰되기는 하였으나, MTBE에 대하여 92%에 가까운 선택도를 보였다. H-Mordenite에 있어서도 DME와 MTBE가 생성되었지만 MTBE에 대한 전환율과 선택도는 ZSM-5 계열보다 현저하게 낮았으며, 반응시간이 길어짐에 따라 심한 활성감퇴가 일어났다. HY의 경우에는 i-C₄H_8의 重合에 따른 C_8-olefin의 生成率이 높았으며, H-Mordenite와 마찬 가지로 반응시간이 길어짐에 따라 觸媒의 비활성화가 관찰되었다. MTBE에 대한 전환율과 선택도는 i-C₄,H_8/CH₃OH의 몰比가 커짐에 따라 증가되었으며, i-C₄H_8의 HZSM-5 細孔內部로의 확산이 상재적 상대적으로 큰 저항을 받음을 알 수 있었다. 溫度가 상승됨에 따라 MTBE의 分解反應이 앙진되었으며, 모든 경우에 80℃의 반응온도가 合成에 적합하였다. Vapor phase reaction of methanol with iso-butylene to form methyl tert-butyl ether (MTBE) has been conducted using HZSM-5, HZSM-11, H-Mordenite and HY catalysts. The effects of catalyst types and reaction conditions on the products distribution have been examined. Determination of acid type and strength of each catalyst used in this experiment were carried out by means of temperature programmed desorption (TPD) of pyridine adsorbed catalysts and IR analysis. The relation of the MTBE selectivities to the acidities and pore characteristics of the zeolite catalysts were studied. On HZSM-5, a small amount of dimethylether (DME) was formed via methanol dehydration, but selectivity to MTBE was close to 92%. DME and MTBE were also formed over H-Mordenite, but selectivity to the latter was considerably lower than HZSM-5. In addition, its severe deactivation occurred upon prolonged use. Significant amount of C_8-olefin was formed in addition to MTBE with HY which also deactivated quickly. As iso-butylene/methanol ratio increased, the conversion and selectivity to MTBE have been greatly enhanced indicating the restricted access of iso-butylene to the HZSM-5 pore structure. The decomposition of MTBE becomes important as the reaction temperature is raised, and shows adequate temperature for the MTBE synthesis to be about 80℃.

Decomposition and Conversion of Carbon Dioxide Into Synthesis Gas Using Thermal Plasma

Kim, Geon Joong,Yun, Sang Heug,Park, Dong Wha 한국공업화학회 1997 Journal of Industrial and Engineering Chemistry Vol.3 No.4

The thermodynamic equilibrium calculations of the direct decomposition of CO₂, the reaction of CO₂ with CH₄, the reaction of CO₂ with a mixture of CH₄ and O₂, and the reaction of CO₂ with H₂ were performed in the temperature range of 500K∼6,000K at atmospheric pressure. The direct decomposition of CO₂, the reaction of CO₂ with CH₄, the reaction of CO₂ with a mixture of CH₄ and O₂, and the reaction of CO₂ with H₂ were studied using thermal plasma as a heating process and a water-cooled tube as a quenching process. The typical plasma power was 4.8㎾ at atmospheric pressure. The conversion into carbon monoxide of the direct decomposition of carbon dioxide was found less than 11%. The conversion of the reaction of carbon dioxide with reactant gas(CH₄ or H₂) was much higher than the conversion of the direct decomposition of carbon dioxide. The effects of CH₄ on the conversion of CO₂ are better than the effects of H₂. The maximum conversion obtained in this work was 89%.

STRUCTURE AND ACIDITY MODIFICATION OF MORDENITE THROUGH ISOMORPHOUS Fe SUBSTITUTION

Kim, Geon Joong,Ahn, Wha Seung 한국화학공학회 1992 Korean Journal of Chemical Engineering Vol.9 No.2

A series of Fe-modified mordenite were hydrothermally synthesized. The effects of substrate composition, aging time, reaction temperature, and reaction time upon the crystallization of the mordenite were investigated. Isomorphous substitution of Fe was confirmed by FT-IR and EPR analysis. Acid strength and acid sites distribution of each catalyst were measured by pyridine TPD, which showed that the number of strong acid sites in H-Fe-mordenite are smaller than in H-Al-mordenite. Structural characteristics and thermal stability were also examined using XRD, SEM and TG. Fe-substitution into the mordenite structure have resulted in substantial decrease in thermal stability. H-Fe-mordenite catalysts showed high selectivity towards p-xylene in toluene alkylation and in xylene isomerization reaction, compared with those obtained using H-Al-mordenite because of lower concentration of strong acid sites. In addition, these H-Fe-modified mordenite showed little hexane cracking activity. Deactivation in both toluene alkylation and xylene isomerization reaction and coke formation over H-Fe-mordenite in these reactions were negligible.

Hβ- zeolite 촉매상에서 Toluene 의 불균등화 반응

김건중,안화승,박기모 한국공업화학회 1997 응용화학 Vol.1 No.2

In this study, the catalytic activity of H_β-zeolite was examined in the disproportionation of toluene. The catalytic activity and selectivity to p-xylene for the disproportionation of toluene was dependent on the reaction temperature, the type of impregmented ion and the amount of impregmented ion, the type of carrier gas and the time on stream. P₂O_5 loaded H_β-zeolite showed the higher para-selectivity as compared to pure H_β-zeolite. This phenomenon may be interpreted in terms of shape selectivity arising from the partial blocking of pore or acidity modification.

ZSM - 5 및 Silicalite - 1 의 합성(2) : 결정화에 미치는 pH 의 영향 Effect of pH on Crystallization

김건중,조병린,안화승,권이묵 한국화학공학회 1989 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.27 No.2

Zeosil 77과 sodium silicate solution을 silica 原料로 사용하여 ZSM-5와 Silicalite-Ⅰ을 水熱合成하였으며, 室溫熟成과 水熱反應過程에서의 基質의 pH 변화 및 酸을 添加하여 基質의 pH를 變調하였을 때의 영향을 ZSM-5 結晶核의 生成과 관련하여 검토하였다. 反應基質을 조제하여 熟成하지 않고 ZSM-5를 合成하면 水熱反應의 초기 (誘導期間)에 反應系의 pH가 급격히 감소하다가 그 후로는 일정한 값을 유지하였다. 室溫에서 反應基質을 熟成처리하는 과정에도 非熟成 水熱反應의 초기단계와 마찬가지로 pH가 감소하였다. 이 過程에서의 pH의 감소는 OH^-가 silica粒子와 반응하여 silanol 또는 각종 silicate 이온을 형성하면서 前驅體 및 核을 이루는 反應에 관여하였기 때문인 것으로 추측된다. 組成이 11.7 Na₂O-A1₂O₃-90 SiO₂-3510 H₂O-10.8 TPABr인 反應基質(pH ; 13.2)에 황산을 첨가하여 pH를 조절한 다음 熟成처리하지 않고 바로 ZSM-5를 合成하였을 때, 基質의 pH를 11.5-11.0으로한 경우에 가장 좋은 결과를 나타내었다. 또한 反應基質의 Na^+ 함량과 pH가 높아 순수한 ZSM-5를 얻기에 부적합한 組成인 30.6 Na₂O-Al₂O₃-90 SiO₂-5049 H₂O-9.0 TPAOH에서도, 황산을 첨가하여 基質의 pH를 13.7에서 11.0으로 조절하면 비교적 단시간 내에 고순도의 ZSM-5를 合成할 수 있었다. Al을 함유하지 않는 Pentasil zeolite인 Silicalite-I의 合成에 있어서는 ZSM-5 경우보다 빠른 結晶化速度를 나타내었으며, ZSM-5와는 달리 황산을 첨가하여 基質의 pH를 13.1에서 11.0으로 낮추고 합성 처리하였을 때 結晶生成이 억제되었다. TPA^+源으로서 TPABr을 사용한 경우가 等몰의 TPAOH를 사용한 때보다 더 빠른 結晶生成速度를 나타내었는데, 이는 TPABr을 사용한 경우가 ZSM-5의 生成에 보다 적합한 pH를 갖기 때문인 것으로 생각된다. ZSM-5 and Silicalite-I were synthesized hydrothermally using Zeosil 77 and sodium silicate solution as silica sources. The variations of pH in the aging step at room temperature and during the hydrothermal reaction period, and the effect of modification of pH with sulfuric acid were investigated in relation to the nucleation process of the zeolites. Without aging treatment, pH of the substrate was decreased significantly during the induction period, but it approached to a constant value asymptotically after the induction period. The same phenomena have been observed in the aging step, which seem to be a consequence of the nuclei being formed by the reaction of OH^- with silica particles producing silanol or soluble silicates ions. For the synthesis of 7SM-5 from the substrate composition of 11.7 Na₂O-Al₂O₃-90 SiO₂-3510 H₂O-10.8 TPABr, by adjusting pH of the substrate with sulfuric acid and without aging, the best result was obtained from the substrate which the pH was adjusted to 11.5-11.0 from 13.2 of originals. Even from a substrate which has unsuitable composition for ZSM-5 synthesis due to high Na^+ content and pH, i.e. 30.6 Na₂O-Al₂O₃-90 SiO₂-5049 H₂O-9.0 TPAOH, ZSM-5 in high purity could be obtained by adjusting the pH of the substrate to 11.0 from 13.7 with H₂SO₄. The faster crystallization rate was resulted in the synthesis of Silicalite-I than in ZSM-5, and the rate of Silicalite-I crystallization, in contrast to ZSM-5, was inhibited by controlling pH of the substrate from about 13 of original to 11.0. Formation of Silicalite-I, a Al-free Pentasil zeolite, prefers a bit higher pH of the substrate than for ZSM-5. As the template, the rapider reaction rates were achieved with TPABr than with TPAOH, probably owing to the preferable pH of the substrate by using TPABr.

Case Study for Natural Gene Transfer from Genetically Modified Food to Food Microorganisms

Dong-Wha Shin,Sun-Hee Park,Geon-Jo Woo,Hae-Yeong Kim,Cheon-Seok Park 한국식품과학회 2004 Food Science and Biotechnology Vol.13 No.3

Structure and Acidity Modification of Mordenite Through Isomorphous Fe Substitution

Kim, Geon Joong,Ahn, Wha Seung 한국화학공학회 1992 NICE Vol.10 No.4

A series of Fe-modified mordenite were hydrothermally synthesized. The effects of substrate composition, aging time, reaction temperature, and reaction time upon the crystallization of the mordenite were investigated. Isomorphous substitution of Fe was confirmed by FT-IR and EPR analysis. Acid strength and acid sites distribution of each catalyst were measured by pyridine TPD, which showed that the number of strong acid sites in H-Fe-mordenite are smaller than in H-Al-mordenite. Structural characteristics and ermal stability were also examined using XRD, SEM and TG, Fe-substitution into the mordenite structure have resulted in substantial decrease in thermal stability HFe-mordenite catalysts showed high selectivity towards p-xylene in toluene alkylation and influent isomerization reaction, compared with those obtained using H-Al-mordenite because of lower concentration of strong acid sites. In addition, these H-Fe-modified mordenite showed little hexane cracking activity. Deactivation in both toluene alkylation and xylene isomerization reaction and coke formation over H-Fe-mordenite in these reactions were negligible.

복합재 격자구조물의 점검창 형상에 따른 구조 안전성 해석

김동건(Dong-Geon Kim),김민식(Min-Sik Kim),배주찬(Joo-Chan-Bae),손조화(Jo-Wha Son),이상우(Sang-Woo Lee) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.11

On fuzzy ideals of a near ring

Chung, Bong-Wha,Kim, Geon-Ho,Park, Se-Won 성균관대학교 기초과학연구소 1995 論文集 Vol.46 No.1

준환상의 퍼지 ideal에 대한 이론은 Salah Abou-Zaid에 의해 소개 되었다. 본 논문에서는 S_2의 성질을 갖는 준환에서, 준환이 regular일 필요·충분조건은 퍼지 좌-ideal B와 퍼지 우-ideal A에 대하여, A·B=A∩B임을 밝힌다.

The Effect of Catalyst on the Decomposition of Dilute Benzene Using Dielectric Barrier Discharge

Park, Dong-Wha,Yoon, Sung-Hwan,Kim, Geon-Joong,Sekiguchi, Hidetoshi 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.4

One of the effective methods for removal of volatile organic compounds (VOCs) is using the combination of non-thermal plasma discharge and catalyst. The experiments were conducted to investigate benzene decomposition in air stream by dielectric barrier discharge (DBD)-catalyst hybrid system. Several types of catalysts such as Ti0_2 (JRC-TI05), Pt/Ti0_2 and V_20_5/TiO_2 had been selected and attached on one glass barrier in the DBD plasma reactor to investigate the catalytic activities. Non-thermal plasma chemical decomposition of dilute benzene was investigated at different range of discharge voltage and residence time at atmospheric pressure. It is shown that the DBD and I wt% V_20_5/TiO_2 catalyst hybrid system is the effective method in decomposing benzene in air stream and controlling byproducts such as CO, CO_2 and N_20 at the same discharge voltage and gas residence time.